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<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <script>
    var obj = { foo: 123 }

    console.log(obj)

    setTimeout(function () {
      obj.foo = 456
      console.log(obj)
    }, 3000)
  </script>
</body>
</html>
